The game of golf has always been closely linked to the equipment used to play the game itself. Although the actual game of golf has not changed much since its inception in the early days of Scotland, the equipment used to play the game of golf has made significant transformations. Although it is debatable which of the numerous golf equipment's have changed the most since the early days of golf, it is hard to argue that the current state of a metalwood type golf clubs is a dramatic deviation from the persimmon woods originally used during the early stages of the game of golf.
Metalwood clubs, based on their inherent design, improve upon the performance of a persimmon wood type golf club head by creating a hollowed metallic shell; which in turn, may drastically increase the coefficient of restitution of the golf club head by allowing the striking face to deflect during impact. In addition to increasing the coefficient of restitution, metalwood type golf club heads have made the game of golf easier for the average golfer by increasing the moment of inertia of the golf club head, which results from the increase in size while maintaining the stability of the golf club through impact.
Despite all the performance gains above, golf club designers have pushed the performance boundary even further by varying the thicknesses of the back of the striking face of the golf club head. Varying the thickness of the back portion of the striking face of the golf club head improves the performance of the golf club head by adjusting the flexural stiffness of the striking face of the golf club head to strategically improve the size and shape of the sweet spot on the striking face; wherein the sweet spot is defined as the portion of the striking face capable of achieving a high coefficient of restitution.
U.S. Pat. No. 6,319,150 illustrates one of the earlier attempts at varying the thickness of the face wall to maximize face strength with minimum face mass. U.S. Pat. No. 6,319,150 provides a golf club that increases the maximum size of the hitting face of the golf club that is usable by having a varying thickness to allow for additional weight to be saved and placed at strategically placed at alternative locations to improve the moment of inertia of the golf club head.
Although these early attempts at adjusting the thickness of the striking face of the golf club head are admirable in providing a foundation for the future development of this concept, most of them do not fully realize the performance benefits that can be achieved by optimizing the size, shape, and geometry of the variable thickness profile at the rear of the striking face based on the size, shape, and geometry of the striking face. U.S. Pat. No. 6,652,391 shows one attempt at varying the size, shape, and geometry of the striking face of the golf club head in an attempt to improve the performance, but it fails to correlate it to the size, shape, and geometry of the striking face itself. More specifically, U.S. Pat. No. 6,652,391 discloses a front wall that varies in thickness and has a bulging area of increased thickness on its inner surface. The bulging area of increased thickness includes a generally ring shaped mass that projects rearwardly from the front wall. A generally cone shaped mass, that also projects rearwardly from the front wall, may be located inside the ring shaped mass.
U.S. Pat. No. 6,997,820 provides another example of an alternative attempt to adjust the size, shape, and geometry of the thickness geometry behind a striking plate to further improve upon the fundamental concept of a golf club having a variable thickness face. In doing so, U.S. Pat. No. 6,997,820 discloses a face plate having a vertical zone of increased thickness and a central region having a reduced thickness. An upward extension of the vertical zone comprises divergent segments separated by an upper region of reduced thickness.
U.S. Pat. No. 7,137,907 provides a further example of another completely different geometry used to adjust the performance of a striking plate of a golf club head. More specifically, U.S. Pat. No. 7,137,907 discloses a face insert having an interior surface with a first thickness section and a second thickness region. The first thickness section preferably has a thickness that is at least 0.025 inch greater than the thickness of the second thickness region.
U.S. Pat. No. 6,623,377 provides yet another example of an attempt to adjust the performance of the golf club head by changing the thickness of the striking face. More specifically, U.S. Pat. No. 6,623,377 discloses a golf club head having a striking plate with regions of varying thickness having a central region of a first thickness that is thicker than the thickness range of any other region. The thickness of the regions decreases outward from the center.
Despite numerous attempts at adjusting the size, shape, and geometry of the rear surface of the striking face of a golf club head, none of the above mentioned patents have investigated the relationship between the size, shape, and geometry of the striking face as it relates to the geometry of the overall geometry of the striking face itself. A golf club with an optimized striking face in terms of its size, shape, and geometry, may greatly improve the coefficient of restitution of the golf club head as well as increase the sweet spot of the golf club head.
Hence, as it can be seen from above, despite all the advancement in golf club technology, the current art has not carefully examined the relationship between the size, shape, and geometry of the striking face as it relates to the size, shape, and geometry of the variable face thickness profile behind the striking face. The current art, despite its numerous attempts at varying the thickness of the striking face, falls short by using random geometries that do not completely optimize the performance capabilities of a golf club head as it relates to the striking face itself. Ultimately, it can be seen from above that there is a need in the art for a golf club head that has a variable thickness geometry that optimizes the size, shape, and geometry of the various thickness levels as it relates to the striking face of the golf club head itself.